Automation Of Feedback System For Pressure Control And Operation of Dc Pulsing Unit For Stable Plasma Production

Abstract

Plasmas are widely used in industries for the manufacturing of semiconductor devices, solar cells, improving the surface hardness of machining tools and depositing value aided coatings on substrates. Plasma properties are studied in the laboratory with the basic aim to confine very hot plasma in magnetic vessel to generate electricity from fusion reaction. Precise controlling of plasma parameters is therefore necessary for the stable plasma operation of the discharge plasmas in both industrial and various basic plasma applications. In order to achieve the above objective, the external parameters governing the state of the discharge conditions need to be controlled and monitored. This includes the operating gas pressure in the discharge chamber, sensors to monitor the pressure using pressure sensor gauge and power supply unit that regulates the input voltage in pulsed mode.

In this project we demonstrated one of the mechanisms to maintain stable plasma operation by controlling the neutral density inside the discharge plasma. This is achieved by developing a real-time feedback control system using PID (Proportional Integral Derivative) to control and set the pressure variable using a combination of Mass Flow Controller and a pressure sensor gauge. In addition a program is developed in LabVIEW to vary the duty-cycle and frequency of D.C pulsing unit.